Fragile X syndrome (FXS) is the most common inherited form of developmental disability. FXS is inherited from the carrier parent, most often the mothers. FXS is associated with severe interfering behavioral symptoms which include anxiety related symptoms, attention deficit hyperactivity, and aggressive behaviors. Approximately 25-33% of individuals with FXS also meet criteria for autistic disorder. The hypothesis of this study is that treatment with acamprosate will reduce inattention/hyperactivity, language impairment, irritability, social deficits, and cognitive delay in youth with FXS. The purpose of this study is to investigate the effectiveness and tolerability of acamprosate in youth with Fragile X Syndrome and to assess the potential psychophysiological differences between FXS and autism spectrum disorders.

The Clinical Global Impression - Severity scale (CGI-S) is a 7-point scale that requires the clinician to rate the severity of the patient's illness at the time of assessment, relative to the clinician's past experience with patients who have the same diagnosis. Considering total clinical experience, a patient is assessed on severity of mental illness at the time of rating 1, normal, not at all ill; 2, borderline mentally ill; 3, mildly ill; 4, moderately ill; 5, markedly ill; 6, severely ill; or 7, extremely ill.

Secondary Outcome Measures:

The Aberrant Behavior Checklist (ABC) [ Time Frame: Week 10 ]

The Aberrant Behavior Checklist (ABC) is a 58-item rating scale used to assess maladaptive behaviors across five original subscales: Irritability (15 items from 0-45), Social Withdrawal (16 items from 0-48), Stereotypy (7 items from 0-21), Hyperactivity (16 items from 0-48), Inappropriate Speech (4 items from 0-12). Additionally, Social Avoidance, a newly developed four-item subscale (from 0-12) of the ABC that captures core social avoidance aspects of Fragile X Syndrome is reported. All items on the ABC are rated from 0 (not at all a problem) to 3 (the problem is severe in degree). Higher scores indicate greater maladaptive behaviors. Differences between Baseline and Week 10 are used as an indicator of change.

Social Responsiveness Scale [ Time Frame: Week 10 ]

The 65-item SRS is a standardized measure of the core symptoms of autism. Each item is scored on a 4-point Likert scale. The score of each individual item is summed to create a total raw score. A total scores results are as follows: 0-62: Within normal limits 63-79: Mild range of impairment 80-108: Moderate range of impairment 109-149: Severe range of impairment

The Children's Yale-Brown Obsessive Compulsive Scales-Modified (CY-BOCS) is a 5-item, semi-structured clinician rating scale modified designed to rate the current severity of repetitive behavior in children and adolescents with PDD. Once the current repetitive behaviors are identified, they are separately rated on 5 items: Time Spent, Interference, Distress, Resistance, and Control. Each of these items is scored on a 5-point scale form 0 (least symptomatic) to 4 (most symptomatic). The CY-BOCS yields a Total Score from 0 to 20 and is sensitive to change.

ADHD Rating Scale 4th Edition [ Time Frame: Week 10 ]

The ADHD Rating Scale is an 18-item scale directly derived from DSM-IV criteria for Attention Deficit Hyperactivity Disorder. The ADHD Rating Scale-IV is completed by the parent and scored by a clinician. The scale consists of 2 subscales: inattention (9 items) and hyperactivity-impulsivity (9 items). If 3 or more items are skipped, the clinician should use extreme caution in interpreting the scale. The total score can range from 0 to 54, with a higher score indicating greater severity.

The VABS-II is a semi-structured interview designed to assess adaptive functioning in communication, daily living, socialization and motor skills. Recognizing that language is a major area of impairment in the study population, the Communication Domain (99 Items from 0-198), in particular the Expressive Subdomain (54 Items from 0-108) are of interest in this study. Items arranged in a developmental sequence are rated on a 3-point scale. Each item is scored from 0 (never performs the behavior) to 3 (usually performs the behavior independently). Higher scores indicate higher adaptive functioning. Differences between Baseline and Week 10 are used as an indicator of change.

Peabody Picture Vocabulary [ Time Frame: Week 10 ]

The Peabody Picture Vocabulary Test is one of the most commonly used assessment tests that measure verbal ability in standard American English vocabulary. This test has been nationally standardized using examinees from various age groups, from children to adults. Thus, the raw scores are equated to mental age, using the norms obtained from standardization. The total standard scores range from 40 (worse receptive vocabulary) to 160 (better receptive vocabulary). The scores can also be converted to percentile rank.

Subjects of child bearing age of both genders will be required to utilize birth control as applicable.

Exclusion Criteria:

Diagnosis of schizophrenia, another psychotic disorder, bipolar disorder or alcohol or other substance abuse based on Diagnostic and Statistical Manual Fourth Edition-Text Revised (DSM-IV-TR).

A significant medical condition such as heart, liver, renal or pulmonary disease or unstable seizure disorder.

Females with a positive urine pregnancy test

Creatinine clearance of less than 30.

Concomitant use of another glutamatergic agent (memantine,riluzole, d-cycloserine, amantadine topiramate, gabapentin, among others.

Evidence of hypersensitivity to acamprosate or potentially serious adverse effect.

Subjects who, in the opinion of the investigator, are unsuitable in any other way to participate in this study including being unable to comply with the requirements of the study for any reason.

Contacts and Locations

Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study.
To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below.
For general information, see Learn About Clinical Studies.

Please refer to this study by its ClinicalTrials.gov identifier: NCT01300923